Superhydrophobic acid-resistant fluorinated Zif-8 prepared at normal temperature and pressure

Abstract

ZIF-8 has a wide range of potential applications, including gas adsorption and storage, molecular separation, chemical sensing, catalysis, and water purification, however, its low stability in acidic environments limits its practical application. Here, a fluorinated ZIF-8 at normal temperature and pressure was synthesized by using hybrid organic ligands, the obtained fluorinated ZIF-8 has high superhydrophobic and acid-resistant properties. A well-designed fluorinated ligand (FL) has trifluoromethyl, triazol and phenolic hydroxyl groups in the molecular structure, which are responsible for hydrophobic character, coordination site and further modifiable site, respectively. With increasing the hybrid ratio of FL, the water contact angle (WCA) of fluorinated ZIF-8 significantly increases. After further post-synthetic functionalization with heptafluorobutyric anhydride, the 20 mol% FL hybrid ZIF-8 (ZIF-8–20 %FL-7F) maintained its inherent high porosity and adsorption capacity, while exhibiting superhydrophobicity and acid resistance. It was loaded on a PP membrane to prepare a ZIF-8–20 %FL-7F@PP composite membrane, which can steadily achieve high-efficiency oil–water separation under acidic conditions with pH 2. This work demonstrates a universal and promising strategy to enhance the availability of the framework material in extreme environments.